Recent lens devices of electronic still cameras are provided with an actuator in the lens barrel in order to obtain the required compactness. Such lens devices use a flexible printed circuit board to connect a unit including a shutter to the control part of the camera body so that the shutter and diaphragm are controlled from the camera body. The flexible printed circuit board is provided in a lens barrel with a loop structure so that it can tolerate shifts due to zooming and retraction of the lens barrel. The loop structure is positioned within a through-channel formed in the lens barrel so as to prevent problems associated with shifting.
In general, the flexible printed circuit board has a band shape with both ends wider than the center part that provides a connecting structure. A through-channel formed in the lens barrel has nearly the same width as the connection ends so that the ends of the flexible printed circuit board can be inserted into the channel. However, the through-channel having nearly the same width as the connection ends of the flexible printed circuit board allows the center part of the flexible printed circuit board to have crosswise play. This causes problems with the shifting of the loop.
In order to prevent these problems, as shown in FIG. 16, a partition 93 having a certain height is conventionally provided in the through-channel 92 formed in the lens barrel 91. The partition 93 regulates the crosswise movement of the flexible printed circuit board. The partition 93 is formed in the through-channel 92, leaving a space 94 that allows the connection ends of the flexible printed circuit board to pass. The connection ends are inserted through the space 94 and the partition 93 prevents crosswise movements of the inserted flexible printed circuit board.
Instead of inserting the flexible printed circuit board in a through-channel so as to prevent problems, Examined Japanese Utility Model H04-22332 uses a separate guide mechanism for the flexible printed circuit board to prevent the problems of the flexible printed circuit board. Japanese Laid-Open Patent Application 2001-235667 describes an alternative structure in which a partition is provided after the flexible printed circuit board is inserted in the through-channel.
In a method in which a partition is provided in the through-channel to prevent crosswise movement of the flexible printed circuit board is shown in FIGS. 17A-17C. However, the loop may be caught by the top or step 93a of the partition 93 or may be trapped in the space when it shifts. This may damage the flexible printed circuit board 60. In addition, passing the connection ends through a narrow space makes the assembly process difficult.
The prior art structure, as shown in FIGS. 16 and 17A-17C, is designed based on the idea that the loop 60d of the flexible printed circuit board 60 will stay in the space 94 as shown in FIG. 17B. However, the loop 60d may occasionally come out of the space 94 of the through-channel 92 as shown in FIG. 17C. That results in problems with the flexible printed circuit board 60. Alternatively, using a separate guide mechanism for the flexible printed circuit board disadvantageously increases the size of the lens device. Providing a partition after the flexible printed circuit board is inserted is not preferred because this increases the number of assembly steps.
The present invention is related to a lens device in which a flexible printed circuit board can be easily assembled and to a method of assembling the flexible printed circuit board in the lens device. In particular, the present invention relates to a lens device that can be used with a camera having a retractable lens barrel.